Robert Hett

Enantio- and diastereoselective synthesis of all four stereoisomers of formoterol

Abstract Enantioselective syntheses of all four stereoisomers of formoterol are accomplished using asymmetric catalytic borane reductions with chiral oxazaborolidines as reducing agents.

Pd-catalyzed aminations of aryl triazolones: Effective synthesis of hydroxyitraconazole enantiomers

Abstract A palladium-catalyzed amination of triazolone 3 by piperazine 2 was used as the key step in an efficient synthesis of highly enantiomerically-pure hydroxyitraconazole isomers. Compound 2 (>99%ee) was prepared by reaction of an achiral phenol precursor with the corresponding dioxolyl tosylate (>99% ee), and 3 was made by alkylation of 6 with 7 (>99%ee).

Conformational toolbox of oxazaborolidine catalysts in the enantioselective reduction of α-bromo-ketone for the synthesis of (R,R,)-formoterol

Abstract Several conformationally constrained oxazaborolidine catalysts have been evaluated in the reduction of ketone 1 . Readily accessible (1R, 2S) 1-amino-2-tetralol (BH) derived oxazaborolidine catalyst ( 6b ) proves to be the most effective and practical catalyst in the reduction of bromo-ketone 1 (96% ee).

Efficient stereoselective synthesis of cis,syn-hydroxyitraconazole isomers

Abstract The first stereoselective synthesis of cis , syn -hydroxyitraconazole isomers via a tricomponent coupling strategy is described. The isomers are prepared from two chiral subunits and connected via an achiral linker. A highly stereoselective route to the cis , syn -isomers is presented.